Bulltear Ad
Page 2 of 2 FirstFirst 12
Results 11 to 17 of 17

Thread: Real world low compression vs. high compression

  1. #11
    Thank you from BT Ultra tech
    Join Date
    Jan 2004
    Location
    Michiana
    Posts
    457
    I'm not into the lil engines, but I think I would be finding a way to adjust the timing before I went to all the expense of hotrodding it!!!

    Maybe an MSD solution?

    If the engine is setup correctly you shouldn't have to take the timing out anyway. I run 38 total on my V8s, and if they ping, it is a problem that needs to be addressed, not detuned.

    I just got done reading an article on the AMC Forum where they fully modded a small AM V8 (304 w/390 crank) for a crap-gas only dyno shootout. They were over 11.5~1 and made over 600HP!!!

    Nobody said you had to keep the 4.0, either. The old Rambler 199 is WAY stronger & capable of outstanding HP & TQ numbers with a good rebuild & a boneyard turbo. The 199 AM 6 popper modified for Indy with a turbo made 640HP. With factory crank & rods, I believe.
    .................................................. .................................................. .........
    '69 BigBadOrange AMX 390. Former NHRA 'Hot Rod", 9.80s @ mid 130s. Hurst/Airheart front discs brakes.
    Nostalgia ProStock.

    '71 AMX 401 w/5-speed Richmond RR trans. 4 wheel disc. 500++ HP. Nostalgia TransAm.
    .................................................. .................................................. .........
    mailto: dhoelcher@Comcast.net GPS: 41.78, -86.24

  2. #12
    Thank you from BT ULTRA TECH MASTER!!!
    Join Date
    Jun 2004
    Location
    Central City, Colorado
    Posts
    1,626
    Well I don't know why I thought you were building a 258.. but hell with the 4.0 seems Jet performance has a flash programmer for that.. and as to the fuel mileage.. you would have to do some serious modding to get that injected 4.0 below 10 mpg



    By the way, I'm not being a smartass here Holeshot, just curious..if backing the timing off a pinging engine is "detuning" how (other than water injection which is meant to be used occaisinally not constantly) how do you address it? seems to me you either back the advance off up the octane or lower the compression? which two of the three would be "detuning" just curious if there may be another technique out there.
    "A man's got to know his limitation's"

    Dirty Harry.

  3. #13

    Join Date
    Apr 2005
    Location
    Cullman, AL
    Posts
    129
    Any more advice on a good quench height to go with, and any input on possiable pushrod length problems with the milling of the block and the thinner head gasket?

    Thanks for all your help so far.
    79 Cherokee, 401, T-18/D-20 hydroboost, otherwise stock.
    Soon to come: Caddy 500,NV4500, NP205, high pinion D-60 front, D-70 rear, SOA, 5.13 gears and 35X12.50's on re centered H1 beadlock wheels

  4. #14
    Thank you from BT Ultra tech
    Join Date
    Jan 2004
    Location
    Michiana
    Posts
    457
    I'll stay with .045" as the distance required for optimum flame propagation. Hydraulic lifters will take up the trivial amount of difference in pushrod length, but if you are changing other valve gear & cam, check with the cam grinder to get all of his specs.
    .................................................. .................................................. .........
    '69 BigBadOrange AMX 390. Former NHRA 'Hot Rod", 9.80s @ mid 130s. Hurst/Airheart front discs brakes.
    Nostalgia ProStock.

    '71 AMX 401 w/5-speed Richmond RR trans. 4 wheel disc. 500++ HP. Nostalgia TransAm.
    .................................................. .................................................. .........
    mailto: dhoelcher@Comcast.net GPS: 41.78, -86.24

  5. #15

    Join Date
    Apr 2005
    Location
    Cullman, AL
    Posts
    129
    I havent decided yet on a cam. I dont know what would be the best to choose. I dont want one too big, but I dont want one too small. Any help you can give me here I can really use.

    Heres comps page:
    http://www.compcams.com/Technical/Ca...HTML/20-25.asp

    They have several listing for the I-6's. The 68-232-4 is the only one of them they list for fuel injection. Its says good torque and smooth idle with a rpm range of 800-4800. The other one I am looking at is the 68-231-4. Its listed as excellent torque and throttle response, 800-5000 rpm range. It has a hair more exhaust duration, a hair more lift on both, and a hair smaller lobe seperation angle Than the first one. Now I have no idea what all that means (I am stupid when it comes to what all these cam numbers mean and how they effect the way the engine runs) I was just strictly looking at the numbers.
    79 Cherokee, 401, T-18/D-20 hydroboost, otherwise stock.
    Soon to come: Caddy 500,NV4500, NP205, high pinion D-60 front, D-70 rear, SOA, 5.13 gears and 35X12.50's on re centered H1 beadlock wheels

  6. #16
    I wouldn't trust a page that gives you the same recomendation for a 290 as they do for a 401.

    When it comes to camshafts, there is no such thing as a "universal" application. Each engine is different and responds differently to camshafts.
    1977 AMC Jeep Cherokee: 360/TH400/1339/44/44 - Beavis
    1984 AMC Jeep CJ7: 401/SM465/AtlasII/44/9" - Grimm Jeeper
    1986 Chevy K20: 5.3/4L60/NP241/10b/14b - Tow Rig
    2004 Pontiac GTO: LS1/T56/M80 - :D

    Try out my gear ratio calculator (Now in metric)

  7. #17
    Thank you from BT Ultra tech
    Join Date
    Jan 2004
    Location
    Michiana
    Posts
    457
    I would call the cam maker you prefer with ALL of your proposed engine specs & EXACTLY what you will be doing with the car. They have pros that spend all day at the computer looking at dyno combinations & notes.
    .................................................. .................................................. .........
    '69 BigBadOrange AMX 390. Former NHRA 'Hot Rod", 9.80s @ mid 130s. Hurst/Airheart front discs brakes.
    Nostalgia ProStock.

    '71 AMX 401 w/5-speed Richmond RR trans. 4 wheel disc. 500++ HP. Nostalgia TransAm.
    .................................................. .................................................. .........
    mailto: dhoelcher@Comcast.net GPS: 41.78, -86.24

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Bulltear Ad